title: In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source.
abstract: In situ focus characterization is demonstrated by working at an extreme ultraviolet (XUV) free-electron laser source using ablation technique. Design of the instrument reported here allows reaching a few micrometres resolution along with keeping the ultrahigh vacuum conditions and ensures high-contrast visibility of ablative imprints on optically transparent samples, e.g., PMMA. This enables on-line monitoring of the beam profile changes and thus makes possible in situ alignment of the XUV focusing optics. A good agreement between focal characterizations retrieved from in situ inspection of ablative imprints contours and from well-established accurate ex situ analysis with Nomarski microscope has been observed for a typical micro-focus experiment.
authors.affiliation: Deutsches Electronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany. natalia.gerasimova@xfel.eu
authors.forename: N
authors.initials: N
authors.lastname: Gerasimova
authors.forename: S
authors.initials: S
authors.lastname: Dziarzhytski
authors.forename: H
authors.initials: H
authors.lastname: Weigelt
authors.forename: J
authors.initials: J
authors.lastname: Chalupský
authors.forename: V
authors.initials: V
authors.lastname: Hájková
authors.forename: L
authors.initials: L
authors.lastname: Vyšín
authors.forename: L
authors.initials: L
authors.lastname: Juha